Even among the three most prominent free AV scanners, AVG has been and continues to be the worst based on its ability to accurately detect malicious code. AntiVir and AVAST are both better, with AntiVir being the better choice due to its traditionally lower false-positive rates. In fact, AntiVir has proven itself to be one of the very best scanners period, free or commercial, in many recent tests.

Among commercial scanners, Kaspersky and F-Secure virtually always do well. I personally run F-Secure at home due partially to their excellent products and partially because they are just a great company. Being in the Infosec business myself, their blog is one of my favorite reads.

Here are the results of the last two comprehensive tests from Andreas Cleminti (av-comparatives.org):

Not sure why Clementi doesn't include Trend Micro/PC-Cillin in his tests. From tests in the past, like those run in 2004-2005 over at www.av-test.org, TM always did very well.

Now for some personal experience, FWIW:

A big part of my job is identifying and analyzing malicious code. One of the tools I have at my disposal is an internally-maintained multi-package AV scanner similar to the ones available online at places like www.virustotal.com and www.jotti.org. To be honest, most of what I end up evaluating is Trojan-installing executable files and Trojans themselves. However, in my testing over the past couple of years, AVG consistently fails to detect at an even reasonable rate. Kaspersky does as well as or better than anyone, but that success rate is only about 75% on objects that are known-malicious.

It should be noted that AV in general is less effective at keeping you "safe" online than it used to be.

I'm running AVG free mainly since it doesn't bog down my system. I do have Webroot's new Spy Sweeper and AntiVirus (Sophos) sitting here. I don't want to pay and don't want my systems to slow down. Would AntiVir be better than the webroot software?

I've been running AVG for over 2 years without any viruses or computer problems. Soooo, not sure why AVG is so bad. But that's just me. I still use it in conjunction with the OS's firewall and exceptions.

I've been running AVG for over 2 years without any viruses or computer problems.

I am sorry, but I see this posted at least 1000 times in these types of threads and I am not singling you out, however, this comment means absolutely noting to anyone reading it and trying to decide on an anti virus program for themselves.

It is possible your machine *IS* infected with something and you just don't know it. It is also possible that MY machine is infected and I just don't know it. Therefore stating you are virus free because of XYZ Anti-Virus tool is meaningless to anyone and everyone that reads it.

I've been running AVG for over 2 years without any viruses or computer problems. Soooo, not sure why AVG is so bad.

Same here, we have Anti-Malware installed on over 20 PCs at work without a hitch. We briefly dabbled with PCcillan but it was absolute crap for spyware. Avast is really nice and we're looking at their Server and Professional editions.

I am sorry, but I see this posted at least 1000 times in these types of threads and I am not singling you out, however, this comment means absolutely noting to anyone reading it and trying to decide on an anti virus program for themselves.

It is possible your machine *IS* infected with something and you just don't know it. It is also possible that MY machine is infected and I just don't know it. Therefore stating you are virus free because of XYZ Anti-Virus tool is meaningless to anyone and everyone that reads it.

Yup, and for the 1000th time I snickered when I read it. It should be added to the definitive list of logical fallacies as the "Antivirus Fallacy."

My roommate has two computers. No anti-virus on either.
(1) 6 year old PC (it has Pentium II processor): "I don't go to porn sites on that one. I only check e-mail and ESPN and stuff, so I don't need anti-virus."
(2) New Apple MacBook: "It's a Mac. I don't need anti-virus on a Mac, right?"

It's funny because no matter who you talk to any type of antivirus program is going to be the worse one or the best one. Today it's AVG. Supposedly. Go to a different computer forum and ask the same question and all these "computer experts" will chime in about how AVG is the best and how the ones recommended here are the worse. It's like asking what kind of blank DVD media to buy. I've used Symantec Corp and AVG over the past 5 years and have had zero viruses. I even use those online scanners and they find nothing. So it's not AVG not telling me about a virus.

I reocmmended the AOl link as good alternative free tool that is using the base Kaspersky engine for detection. It is however missing some very good features the real Kaspersky includes.

As the the ratings from the secutiry monitor, yeah I would even waste my time running it and I never suggested anyone run it.

Antivir will slow your computer down. It's good, but requires resources and since most people complain about symantec for the same reason, I thought I would mention it here.

Virus creation has run a course from kids having fun and trying to reak havoc to organized crime trying to turn a profit from it. Now that serious players with resources are in the game, the AV companies are losing and they know it.

My bigger point is that no AV tool can protect you to the point where you can claim with certainty that you have had no infections while using it. Multiple scanners help, but there are things out there that no AV tool can detect and I wish I didn't know that to be a fact.

Virus creation has run a course from kids having fun and trying to reak havoc to organized crime trying to turn a profit from it. Now that serious players with resources are in the game, the AV companies are losing and they know it.

My bigger point is that no AV tool can protect you to the point where you can claim with certainty that you have had no infections while using it. Multiple scanners help, but there are things out there that no AV tool can detect and I wish I didn't know that to be a fact.

Amen to that. Every time I get a new email from SANS, I want to curl up in the fetal position and cry...

Try living it I recently went through a situation where by complete accident we found machines infected with "something".

It was ugly and to this day Symantec can not reliably detect the something and most likely never will.

Been there, done that. When I was sys admin @ an int'l studies grad school, we had a couple of Russian profs who always found a way to pick up some gnarly beasties. I finally resorted to keeping imaged HDDs in my desk just for them...

Diverting back to topic, we used F-Prot/F-Secure back then, and it is a damn good product. I was on a 1st name basis with a few of their techs. Still use it on my home machine.